The present invention relates to an electronic access control device, and more particularly to an electronic lock having a solenoid which increases or decreases resistence to opening the lock.
Electronic locks are well known and have been used to control the functioning of a locking mechanism. In particular, solenoids have been used as part of an electronic lock to restrain a latch that prevents movement of a locking bolt. An example of such a system is shown in Nakauchi, U.S. Pat. No. 4,798,068. Electronic locks have the advantage of allowing the use of electronic keys, which enables such locks to keep track of different keys. However, electronic locks suffer from several disadvantages. First, the locks consume electrical power. Thus, such locks either must be connected to a permanent power source, or must be supplied with a battery. Often, it is not practical to connect an electronic lock to a permanent source of power. Power consumption by an electronic lock, however, can quickly deplete the power in the battery, requiring either large, bulky batteries or frequent replacement of batteries.
Electronic locks which use a solenoid suffer from another disadvantage in that such locks may be opened with a sharp blow to the lock. For example, in the electronic lock disclosed in Nakauchi U.S. Pat. No. 4,798,068, a magnet holds a latch in place, resisting the force of a spring which urges the latch toward an unlocked position. Such a locking mechanism may be unlocked by the expedient of a sharp blow to the outside of the lock. A sharp blow can jar the latch, causing the latch to move or become displaced from the magnet, and thus causing the latch to move to an open position.
Electronic locks may also be susceptible to picking. Electronic locks usually have openings to allow entry of an electronic key to open the lock. However, the openings in the electronic lock may provide access to the inside of the lock and allow the lock to be picked. It is further desirable to install electronic locks on existing cabinets and drawers. However, mounting the locks on the exterior surfaces of the doors may allow access to the mounting screws or bolts. The lock would then be susceptible to being removed from the cabinet or drawer by cutting or drilling out the screws or bolts which attach the lock to the drawer.
Electronic access control devices also can be difficult to use because of the necessity of storing key data within the device. Typically, such devices contain a memory which stores the key codes for electronic keys which are authorized to open the device. The key codes, however, must be entered into the memory. Over time, it may be desirable to update the memory, to add keys or to delete keys which are authorized to access the device. Updating the memory of the installed device to include the new information can be difficult and time consuming. This is typically carried out by connecting the electronic access control device to a computer, which then downloads the key access information to the memory of the electronic access control device. However, inputting the updated key access information and then carrying a computer to the device to update lock information is burdensome and time consuming.
In addition, it is also desirable for each electronic access control device to have a master key which controls access to the device and which may be authorized to perform additional device functions. However, this requires initializing the memory with the master key code. If initialization occurs at the manufacturer, then the device and master key must be kept together and sold as a unit. If initialization occurs after the device is installed, then a computer must be connected to the memory to download the master key information. In either event, entering master key data and maintaining device and master key pairings can be time consuming and difficult.
What is therefore desired is an electronic access control device that utilizes low power, that is not susceptible to opening in response to sharp blows to the device, which does not present openings through which the device may be picked or through which the device mountings may be accessed, which is not easily removed from the exterior surface to which it is mounted and which provides a system for managing key authorization information which is easy to use.
In a first separate preferred aspect of the invention, the present invention provides an electronic access control device having a movable locking member. A locking mechanism is operable to control the locking member. A movement detector generates a first condition in response to movement of the locking member. A key detector generates a second condition in response to detecting a key. The locking mechanism increases resistance to movement of the locking member in response to the first condition, and decreases resistance to movement of the locking mechanism in response to the second condition.
In a second separate preferred aspect of the invention, the electronic access control device has a control mechanism regulated by a computer system. A key detector generates different key codes in response to detecting at least some keys. A computer system stores a plurality of authorized key codes, the computer system being operable to regulate the control mechanism in response to an authorized key code. The computer system stores a master key code in response to a first key code received from the.key detector so that the first key detected by the key detector becomes a master key capable of controlling storage of the authorized key codes.
In a third separate preferred aspect of the invention, an electronic access control device has an enclosure comprised of at least a housing and a base member detachably matingly engageable with one another. The enclosure contains a locking mechanism to control a locking member having respective locked and open positions. The base member has mounting members that attach the base member to a surface. A catch mechanism cooperates with the housing and the base member to limit relative movement therebetween when the housing is matingly engaged with the base member to form the enclosure and the locking member is in the locked position.
The several aspects of the present invention provide at least one or more of the following advantages. The present invention provides an electronic access control device which utilizes only small amounts of power to operate the device. The electronic access control device is also more resistant to opening in response to a blow to the exterior of the device. The invention further provides an electronic access control device which is less susceptible to being picked. In addition, the electronic access control device provides greater protection to the mounting members to prevent removal of the mounting members of the device. Finally, the present invention provides an electronic access control device that enables easy management of keys which are authorized to actuate the device.